1. Field of Invention
The present invention relates to a driver's feeling control apparatus which drives a seat in response to a state of a vehicle.
2. Description of Related Art
Taking the yaw rate and the acceleration to a lateral direction (hereinafter, referred to as “lateral G”) generated by the rotation and revolution movements of a vehicle as representative characteristics, the responses (phase or time constant) of the yaw rate and the lateral G to a steering operation for a turn may be set as indexes for evaluating the maneuverability when turning a vehicle.
A vehicle is considered to be driven with ease when the yaw rate and the lateral G thereof occur in the same phase with respect to steering. Influence over the driving feeling of the human exerted by a phase relation between the yaw rate and the lateral G at the time of turning a vehicle is described in “Technique for Improving Maneuverability of Vehicle” (edited by Society of Automotive Engineers of Japan, Inc.).
A suspension has been conventionally tuned in a manner that the time constants of yaw rate and lateral G for steering are in close agreement, and that the time constants fall within a range of approximately 0.05 s to 0.10 s.
However, in a case of a general vehicle of which front wheels are the only wheels to be steered, a turning motion has one degree of freedom for a steering input with two degrees of freedom for outputs of yaw and lateral motions. For this reason, each of the time constants of the yaw rate and the lateral G cannot be controlled independently. As a result, it is difficult to keep the time constants of the yaw rate and of the lateral G within the above-mentioned ideal range in an actual vehicle which is to be designed to meet the requirements of ride comfort and the like.
On the other hand, there is a conceivable technique to control yaw and lateral motions independently of each other in accordance with the turning operation of the steering wheel, by performing four wheel steering to steer the rear wheels in addition to the front wheels so that the time constant of the lateral G substantially agrees with that of the yaw rate.
In addition to this technique, Japanese Patent Application Laid-open No. Sho 63-151549 discloses a technique for supporting a body against the lateral G by driving the movable part provided to a part of a seat. Additionally, Japanese Patent Application Laid-open No. Hei 7-315088 shows a technique in which a movable part of a seat can be rotated in a yaw direction. When the driver turns his/her upper body around, for example, to move a vehicle backward, the movable part is rotated to follow the driver's upper body.